题目

The most important thing about cotton in history is ____ part that it played in ____ Industrial Revolution. A. / ; /         B. the ; /      C. the ; the      D. a ; the   答案：C人工降雨时利用干冰________（填物态变化）吸热使云层中水蒸气的温度降低最终形成降雨；夏天起风时，人感觉凉快是因为风加速了皮肤表面汗液的________（填物态变化）．